1. Field of the Invention
This invention relates to improvements in helicopter blades with a view to minimizing vibrations in the blades and its supporting structure.
2. Description of the Related Art
Helicopter blades encounter substantial wind forces when they move in relatively horizontal planes or directions as opposed to vertical planes or directions. As the blades rotate they encounter additive or subtractive wind forces, subtractive with the wind and additive against the wind. As they rotate from an additive to a subtractive wind force the substantially instantaneous change in wind direction causes stresses and consequent shocks to the blade system. The resultant shock waves can do great damage to the blades and the support system.
This invention provides hydraulic pistons to minimize the shock as helicopter blades encounter different wind forces. The blades of a helicopter each have a hydraulic cylinder and piston connected to it. The pistons are movable within a cylinder between innermost and outermost positions. The hydraulic fluid of each cylinder is connected to another cylinder by a hydraulic tube or through a manifold. A drive bar connects to the cylinders and is driven by the engine.
As the helicopter moves in flight one of the blades may move against the wind while the other moves with the wind. The force of the wind against a blade causes a first piston to move inwardly. This causes fluid to be expelled from the cylinder into the other cylinder by way of the hydraulic tube. The force of the fluid causes the second piston to be moved outwardly. Meanwhile the second piston, because it is moving with the wind, is exerting an opposite effect on the other piston. The result will be a tendency for the blades to approach an equilibrium condition with respect to the wind forces to minimize the shocks to the overall system.